A study released last spring linked Medtronic Inc.’s Infuse bone growth protein to male sterility that, in some cases, may be permanent. The study, conducted by frequent Infuse critic, Dr. Eugene Carragee, found that 7.2 percent of the men he treated with Infuse during spine surgery developed retrograde ejaculation, compared with 0.6 percent of those who received a traditional bone graft.
Retrograde ejaculation occurs when semen is misdirected into the bladder. According to a report from The New York Times, the study involved 240 patients Carragee had treated several years prior with Infuse or a bone graft. Of those, five of the 69 patients who received Infuse developed retrograde ejaculation, compared to one out of the 174 who underwent the other procedure. The condition resolved itself in only half of the six who developed it.
“It is important that men who are considering having children have the opportunity to weigh the risks of the various available procedures,” said Dr. Carragee, according to The Times.
Medtronic-paid doctors who worked on the clinical trials for Infuse purportedly found no connection between the product and male sterility. While the label for Infuse does note that retrograde ejaculation is a possible side effect, the doctors who conducted the clinical trials for the bone growth protein blamed the problem on the surgical technique used on the patients who developed the condition.
According to the Times, the Medtronic-sponsored Infuse studies specified which surgical techniques was used in each of the men with retrograde ejaculation, but did not indicate whether or not they had received Infuse. In his article, published last May on the website for The Spine Journal, Dr. Carragee questioned the decision not to specify which patients had received Infuse, asserting that was the standard way clinical trial results are presented.
According to a Bloomberg News report, a spokesperson for the device maker said Medtronic had disclosed data to the U.S. Food and Drug Administration showing retrograde ejaculation was a potential side effect of the surgery and broke down the results depending on whether patients received Infuse. However, according to The Spinal Journal report, this potential side effect is not widely known in the medical community.
The New York Times report pointed out that the researchers who authored the Infuse clinical trial, Dr. J. Kenneth Burkus and Dr. Thomas A. Zdeblick, have each received millions of dollars from Medtronic in consulting fees or royalty payments. But both have insisted those financial relationships have not affected their scientific judgment.
But in an editorial accompanying Dr. Carragee’s study, Dr. James D. Kang of the University of Pittsburgh mused that industry support was one way to explain the different conclusions reached by Dr. Carragee and the authors of the Medtronic-sponsored trial, writing that there was not “any rational explanation for these observational differences.”
According to Bloomberg, Dr. Kane also wrote that other spine surgeons have reported various complications with Infuse, including inflammatory reactions, sterile cyst formation, bone damage, and loss of alignment. Life threatening airway complications have also been reported when Infuse was used off-label in the cervical spine, potentially life-threatening airway complications. At the same time, there is no firm evidence that Infuse improves results for patients and it increases the cost of treatment, he wrote
Retrograde ejaculation is just one complication that has been linked to to Infuse, which is made from recombinant human Bone Morphogenetic Protein-2 (rhBMP-2). Over the summer, a critical analysis of 13 Medtronic sponsored clinical trials for Infuse published by Dr. Carragee asserted that the studies failed to report serious complications, including cancer, sterility in men, infections, bone dissolution and worsened back and leg pain, in patients treated with the product. This past fall, Dr. Carragee presented a third study at the North American Spine Society meeting that raised concerns about a possible association between high doses of rhBMP-2 and an increased risk of cancer. According to a report from The New York Times, Dr. Carragee pointed out that Infuse is often administered at higher-than-approved doses when it is used in off-label procedures.
Both the U.S. Justice Department and the U.S. Senate Finance Committee have been conducting ongoing investigations of Medtronic’s marketing of Infuse, and a mounting number of personal injury lawsuits have also been filed by victims of alleged Infuse complications.